Browsing School of Physics by Author "|~|"
Now showing items 1-20 of 36
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The 2009 multiwavelength campaign on Mrk 421: variability and correlation studies
Gillanders, Gary; Lang, Mark; Gillanders, Gary; Lang, Mark; Moriarty, P. (EDP Sciences, 2015-04-17)Aims. We perform an extensive characterization of the broadband emission of Mrk 421, as well as its temporal evolution, during the non-flaring (low) state. The high brightness and nearby location (z = 0.031) of Mrk 421 ... -
Accounting for the fringe magnetic field from the bending magnet in a Monte Carlo accelerator treatment head simulation
O' Shea, Tuathan P.; Foley, Mark J. (American Institute of Physics, 2011)Purpose: Monte Carlo (MC) simulation can be used for accurate electron beam treatment planning and modeling. Measurement of large electron fields, with the applicator removed and secondary collimator wide open, has been ... -
Characterization of an extendable multi-leaf collimator for clinical electron beams
O'Shea, Tuathan P.; Foley, Mark J. (Institute of Physics, 2011)An extendable x-ray multi-leaf collimator (eMLC) is investigated for collimation of electron beams on a linear accelerator. The conventional method of collimation using an electron applicator is impractical for conformal, ... -
Circular polarization of synchrotron radiation in high magnetic fields
de Burca, Diarmaid; Shearer, Andrew (Oxford University Press, 2015-04-17)The general model for incoherent synchrotron radiation has long been known, with the first theory being published by Westfold in 1959 and continued by Westfold and Legg in 1968. When this model was first developed, it was ... -
Design and performance of a small-animal imaging system using synthetic collimation.
Havelin, R. J.; Foley, Mark J. (Institute of Physics, 2013-02-28)This work outlines the design and construction of a single-photon emission computed tomography imaging system based on the concept of synthetic collimation. A focused multi-pinhole collimator is constructed using ... -
Electron beam therapy at extended SSD: a Monte Carlo investigation of output fom a Siemens Oncor linear accelerator
Foley, Mark J.; O'Shea, T. P.; Downes, Patrick A.; Shearer, Andrew (2008)Electron-beam therapy is used to treat superficial tumors at a standard 100 cm source-to-surface distance (SSD). However, certain clinical situations require the use of an extended SSD. In the present study, Monte Carlo ... -
Exceptionally bright TEV flares from the binary LS I+61 degrees 303
Connolly, M.P.; Gillanders, Gary; Lang, Mark (IOP Publishing, 2016-01-20)The TeV binary system LS I +61 degrees 303 is known for its regular, non-thermal emission pattern that traces the orbital period of the compact object in its 26.5 day orbit around its B0 Ve star companion. The system ... -
Experimental and numerical assessment of MRI-induced temperature change and SAR distributions in phantoms
Colgan, Niall; Van der Putten, Wil; Tuohy, Brendan (Springer Verlag, 2017-06)During an MR procedure, most of the transmitted RF power is transformed into heat within the patient’s tissue and implants as a result of resistive losses which is referred to as the specific energy absorption rate (SAR) ... -
FirstNuSTAR observations of MRK 501 within a radio to TeV multi-instrument campaign
Connolly, M.P.; Gillanders, Gary; Lang, Mark (IOP Publishing, 2015-10-10)We report on simultaneous broadband observations of the TeV-emitting blazar Markarian 501 between 2013 April 1 and August 10, including the first detailed characterization of the synchrotron peak with Swift and NuSTAR. During ... -
The Galway astronomical Stokes polarimeter: an all-Stokes optical polarimeter with ultra-high time resolution
Collins, Patrick; Kyne, Gillian; Lara, David; Redfern, Michael; Shearer, Andrew; Sheehan, Brendan (Springer Verlag, 2013-06-28)Many astronomical objects emit polarised light, which can give information both about their source mechanisms, and about (scattering) geometry in their source regions. To date (mostly) only the linearly polarised components ... -
Gamma-rays from the quasar PKS 1441+25: story of an escape
Connolly, M.P.; Gillanders, Gary; Lang, Mark (2015-12-20)Outbursts from gamma-ray quasars provide insights on the relativistic jets of active galactic nuclei and constraints on the diffuse radiation fields that fill the universe. The detection of significant emission above 100 ... -
Improved simulation of small electron fields for external beam radiation therapy
Foley, Mark J.; O'Shea, T. P.; Faddegon, B. A. (2009)This paper reports on improved simulation of small electron fields from a Siemens Primus linear accelerator. Accelerator simulation was performed using the Monte Carlo user code BEAMnrc. Source and geometry parameters ... -
An investigation into the use of MMCTP to tune accelerator source parameters and testing its clinical application.
Foley, Mark J.; Conneely, Elaine (2013)This paper presents an alternative method to tune Monte Carlo electron beam parameters to match measured data using a minimal set of variables in order to reduce the model setup time prior to clinical implementation of the ... -
Investigation of nanoscale structural alterations of cell nucleus as an early sign of cancer
Alexandrov, Sergey (BioMed Central, 2014)Background: The cell and tissue structural properties assessed with a conventional bright-field light microscope play a key role in cancer diagnosis, but they sometimes have limited accuracy in detecting early-stage cancers ... -
An investigation of the Eigenvalue Calibration Method (ECM) using GASP for non-imaging and imaging detectors
Kyne, Gillian; Lara, David; Hallinan, Gregg; Redfern, Michael; Shearer, Andrew (Springer Verlag, 2016-02)Polarised light from astronomical targets can yield a wealth of information about their source radiation mechanisms, and about the geometry of the scattered light regions. Optical observations, of both the linear and ... -
Irish Machine Vision and Image Processing Conference Proceedings 2016
Devaney, Nicholas (Irish Pattern Recognition and Classification Society, 2016)[No abstract available] -
Microcirculation imaging based on full-range high-speed spectral domain correlation mapping optical coherence tomography
Subhash, Hrebesh M.; Leahy, Martin (SPIE (International Society for Optics and Photonics, 2014)Microcirculation imaging is a key parameter for studying the pathophysiological processes of various disease conditions, in both clinical and fundamental research. A full-range spectral-domain correlation mapping optical ... -
Modelling exposure to pharmaceutical agents
Coggins, Marie (Institute of Physics, 2009)Aerosol exposure to the active ingredients of pharmaceuticals arises in research, development and manufacturing. In most instances it is only possible to make small numbers of measurements of exposure and given the inter- ... -
Monte Carlo commissioning of clinical electron beams using large field measurements
O'Shea, Tuathan P.; Foley, Mark J. (Institute Of Physics (IOP Publishing), 2010-07-21)Monte Carlo simulation can accurately calculate electron fluence at the patient surface and the resultant dose deposition if the initial source electron beam and linear accelerator treatment head geometry parameters are ... -
The most powerful flaring activity from the NLSyl PMN J0948+0022
Moriarty, P.; Gillanders, Gary; Lang, Mark (Oxford University Press, 2015-01-21)We report on multifrequency observations performed during 2012 December-2013 August of the first narrow-line Seyfert 1 galaxy detected in gamma-rays, PMN J0948+0022 (z = 0.5846). A y -ray flare was observed by the Large ...